Deep directional electromagnetic logging-while-drilling technology is an enabler of proactive well placement, relying on directional sensitivity measurements and real-time interpretation based on 1D multi-layer model-based inversion, integrated with geological modeling software. New generation of deep directional resistivity tools with reservoir scale measurements enable detection of boundaries and contacts up to 100 feet away from a wellbore, which enables reservoir imaging and optimization of well placement. Hundreds of wells have been drilled using this new technology, some of them in complex geological scenarios, where 1D assumption about the model may not provide enough information and may affect the quality of real-time interpretation.
Over the past decade, much progress has been made in interpretation of deep directional electromagnetic (EM) measurements using 1D multi-layer inversion. As the wells are being placed in more complex scenarios, these models may not be adequate. Placing the well with respect to oil-water contact (OWC) is one application of deep directional well placement technology. In cases where formation layers are dipping, the 1D assumption about the formation breaks down, and a standard inversion-based answer product may not take into account that the tool is close to the OWC and that the OWC may be flat and less conductive than the reservoir.